1. Field of the Invention and Related Art Statement
The present invention relates to an optical microscope with variable magnification, in which a magnification can be changed by rotating a revolver supporting a plurality of objective lenses having different magnifications such that any objective lens having a desired magnification is selectively indexed into an inspection optical axis, while a stage for holding a specimen to be inspected is moved in a plane perpendicular to the inspection optical axis.
Heretofore, there have been developed various kinds of optical microscopes for inspecting enlarged images of specimens, for displaying enlarged images of specimens on a television monitor screen and for taking photographs of enlarged images of specimens. Such microscopes have been widely used in various fields such as industrial and biological factories and laboratories.
In the known optical microscopes used in the above mentioned fields, a plurality of objective lenses having different magnifications are secured to a revolver which is arranged rotatably to index any one of the objective lenses into the inspection optical axis, so that a magnification of an image of a specimen can be varied. Usually, in case of changing the magnification of the inspected image of the specimen, the condition of illumination of the specimen is changed in response to the rotation of the revolver in order to illuminate the specimen in the most effective manner. Moreover, when a low magnification is changed into a high magnification, in order to avoid that a portion of the specimen to be inspected is removed out of the field of view, before the magnification is changed, the stage must be moved such that said portion to be inspected is situated substantially at a center of the field of view.
However, when all the above mentioned operations are carried out manually by the user, a necessary time for adjusting the microscope is liable to be very long and a time for studying the specimen becomes shortened accordingly.
In Japanese Patent Application Publication Kokai Sho Nos. 59-177507 and 59-177508, there is disclosed a microscope in which the illuminating condition is automatically adjusted in response to the change of objective lenses. In Japanese Patent Application Publication Laid-open Kokai Sho No. 60-118827 and Japanese Utility Model Publication No. 62-32244, there is described another known microscope in which the revolver is rotated by means of an electric motor. Further in Japanese Patent Application Laid-open Kokai Sho No. 60-8816, there is disclosed still another known microscope in which the specimen stage is moved by means of an electromagnetic driving means.
In these known optical microscopes, parts of the operations for handling the microscope are effected with the aid of the electromagnetic driving means. That is to say, the revolver and stage are driven by means of the electric motors. However, in order to move the revolver and stage, the user has to operate switches and the like. That is to say, in the known microscope, the revolver and stage could not be driven automatically.
Therefore, when the magnification is to be changed from a low value into a high value, the operation of the specimen holding stage becomes cumbersome and requires a relatively long time. It should be noted that even though a desired portion of the specimen is moved into the center of the field of view, when the revolver is rotated to index an objective lens having a high magnification into the inspection optical axis, the desired portion could not be seen, because parts of the microscope such as the objective lenses and revolver have errors in precision as well as in assembling, so that desired portion of the specimen might be shifted from the center of the field of view. Therefore, in almost all cases, when the magnification is varied into the high magnification, the stage has to be adjusted precisely.
Moreover, when an enlarged image of a desired portion of specimen under inspection is inspected with the low magnification, it is necessary to select an objective lens having a higher magnitude by visually judging a size of the desired portion of specimen on the basis of the image having a low magnification. Sometimes this results in error in selection of an objective lens and requires high user skill level. If the desired portion of the specimen could not be inspected with a desired magnification, it is necessary to select another objective lens. In this manner, in the known microscope, the operation of changing the magnification becomes very cumbersome.
In Japanese Patent Application Laid-open Kokai Sho No. 64-53157, there is disclosed another known optical microscope in which the operation is improved by automating the inspection of a specimen. In this known microscope, predetermined successive steps for checking a specimen are performed automatically, but it is not possible to inspect a desired portion of specimen with a desired magnification.